Wood chipping machine



May 1, 1962 H. w. WEXELL 3,032,281

WOOD CHIPPING MACHINE Filed June 3, 1960 2 Sheets-Sheet l May 1, 1962 Filed June 3, 1960 H. w. WEXELL 3,032,281

WOOD CHIPPING MACHINE 2 Sheets-Sheet 2 United States Patent 3,032,281 WOOD CHIPPING MACHINE Harry W. Wexell, Soderhamn, Sweden, assignor to Sotlerhamns Verkstader Aktiebolag, Soderhamn, Sweden, a corporation of Sweden Filed June 3, 1960, Ser. No. 33,740 Claims priority, application Sweden June '5, 1959 Claims. (Cl. 241-92) The present invention relates to certain improvements in machines for producing wood chips.

More particularly this invention relates to improvements in a Wood chipping machine for producing wood chips from larger pieces of wood such as lumber.

Still more particularly this invention relates to wood chipping machines of the kind having a rotatable chipper disc carrying a plurality of circumferentially spaced cutter knives, the individual knives being secured to the chipper disc by means of a plurality of headed bolt means penetrating through apertures in the knife and elongated apertures in the chipper disc to the rear side of said disc where nuts are threaded on the projecting end of the bolt means.

The cutter knives are subjected to great strains and strong wear so that they must be exchanged within relatively short intervals for resharpening of the cutting edges thereof. The replacement of the knives when of ordinary structure is a complicated procedure requiring much time for which reason the time of effective use of a chipping machine is very limited. If a cutter knife is secured by means of four bolt means, for example, the nuts must be threaded off entirely before the bolt means can be withdrawn. The individual bolt means are subjected to varying strains and thus become deformed differently. For

this reason attention must be paid to avoid mixing of the bolt means and the nuts removed from the machine, which further complicates the replacement work.

One main object of the invention is to provide improvements for simplifying the work involved in the periodical replacement of the cutter knives so as to require but a fraction of the time needed heretofore.

A further object of the invention is to render the still more frequent operation known per se of readjusting the cutter knives in response to their wear before their replacement for the purpose of regrinding easier than hitherto.

According to one main feature of the invention the cutter knife has elongated apertures formed with substantially parallel longitudinal edges fitting to a flattened head of the bolt means so as to cause the knife to be disengaged from said head in a certain angular position of the bolt means but to be locked by said bolt means on tightening of the nut causing the bolt means to turn into an angular position at right angles to its first angular position, a portion of said bolt means located in an aperture, preferably that of the cutter knife, being formed with guide faces adapted to allow rotation of the bolt means through a quarter of a revolution between said angular positions at the utmost.

According to a further feature characterizing the invention a screw spring is positioned around the bolt means, so as with one end to engage a shoulder formed on said bolt means and with its other end a stop forming part of the chipper disc so that the nut when being turned will retain its axial position but cause the bolt means to perform an axial movement with its head.

Further objects and advantages of the invention will become apparent from the following description considered in connection wtih the accompanying drawings which form part of this specification and of which:

FIG. 1 is a perspective view of a portion of a chipper disc seen from the rear side.

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FIG. 2 is a perspective view of a portion of the chipper disc seen from the front side and represented in a larger scale.

FIG. 3 is a perspective view of a bolt means with members disposed thereon and FIG. 4 is a sectional view along line IVIV of FIG. 3.

Referring to the drawings, reference numeral 10 designates a rotatable chipper disc provided with circumferentially equally spaced slots 12 adjacent which cutter knives 14 are located within recesses 16 formed on the front side of the chipper disc, wedge-formed inserts 18 being placed below said knives so as to cause them to be inclined in relationship to the face 20 of the chipper disc extending perpendicularly relative the axis of rotation of said disc. Preferably the edges of the slots 12 opposite the knives 14 are provided with linings 22 usually formed as wear steels and fixed by means of bolts 24 and nuts 26.

The individual knives 14 are retained by bolts generally designated by 30 and in the embodiment shown being four in number for each knife. The bolts extend through elongated bolt holes 32 formed in the disc 10 and are on their ends facing the knife formed'with heads 34 having a flattened and elongated shape and with a conical surface 36 fitting to each of two corresponding and im mediately adjacent conical recesses 38, 40 formed in the knife 14. Said two recesses merge into a co-herent elongated aperture 42 with longitudinal edges extending parallel to one another. The aperture 42 has such dimensions as to disengage the head 34 as long as this latter takes the angular position shown by the bolt 30 in FIG. 2 on the right-hand side. When the bolt is rotated through a quarter of a revolution as is shown in the same figure on the left-hand side the head 34 enters entirely one of the recesses 38 or 40.

On the rear side of the chipper disc 10 the bolts are formed with threads 44 for nuts 46. A washer 48 by means of screws 50 (FIG. 1) is rigidly secured to the disc 10 on the rear side thereof. The washer 48 has apertures 52 in a number corresponding to that of the bolts. The apertures 52 are elongated and have a width fitting to the bolt and are thus smaller than the outer diameter of a sleeve 54 which is positioned above the bolt around the threaded portion 44 thereof. A helical spring 58 is inserted between the sleeve 54 and a shoulder 56 formed on the bolt. The sleeve 54 and the spring 58 are freely movable within the elongated bolt hole 32 of the disc 10. The sleeves 54 of the bolts belonging to one knife 14 bear against the washer 48'commonto all the bolts for the knife in consideration. Therefore, the nuts. 46 when being turned will maintain their axial position while the bolts 30 are displaced axially in a direction outwards from the knives 14 under the actuation of the spring 58 both when the nuts are loosened and when they are tightened. The sleeve 54 serves to prevent the spring 58 from entering the threads 44. In order to provide abutment surfaces taking up the pressure created by the tightening step also laterally of the elongated apertures 52 of the washer 48 a second washer 60 is interposed between the first-mentioned washer and the nuts 46. This second washer has circular holes dimensioned in correspondence to the diameter of the bolt and it is in contradiction to the washer 48 not locked in its position by the chipper disc 10.

Adjacent its head 34 the bolt 30 has a portion 62 having in cross section a generally square shape as will be evident from FIG. 4, which shape fits to the width of the aperture 42 formed in the knife 14. However, two opposite corner edges 64 are rounded off and as a consequence the bolt may be rotated by between the two positions shown in FIG. 2 but not more. In the embodiment shown the rounded corner edges 64 are spaced from the head 34, adjacent which head two diametrically opposite rectangular shoulders 66 are formed. This will result in that with the bolt head 34 located in one of the recesses 38 or 40, respectively, the bolt is blocked against rotational movement in both directions. Not before withdrawal of the bolt a sufiicient distance as to cause the shoulders 66 to leave the aperture 42 can a rotation by 90 of the bolt from the position shown left-hand in FIG. 2 to the position shown right-hand in the same figure be effected.

When the row of knives has become dull and must be replaced, the nuts 46 are loosened and as a consequence the bolt heads 34 are displaced out of the knives. As soon as the shoulders 66 have been withdrawn from the apertures 42 each bolt is automatically rotated by 90 but no more, and takes the position shown right-hand in FIG. 2. Now the knife 14 may be removed and a fresh knife inserted while the bolts are still positioned in the chipper disc. When tightening the nuts again the bolts automatically perform a returning rotational movement to the angular position shown left-hand in FIG. 2.

In order to keep the correct spacing between the cutting edge 28 of the knife 14 and the upper face of the wear steel 22 in spite of varying wear of the knife edge, the bolts 30 are readjusted through lateral displacement within the apertures or bolt holes 32, 52 or correspondingholes 68 formed in the insert 18. The double recesses 38, 40 make it possible to effect an adjustment from one to the other of the two recesses when full use has been made of the longitudinal extension of said apertures or bolt holes. According to FIG. 2 the knife at the outset had a dimension so large as to cause the head 34 of the bolts to be located in the lower recesses 40. In order tomake the knives usable further in spite of considerable wear the bolts have been drawn up along the elongated apertures while the knife has been displaced downwards causing the heads 34 to become located in the upper recesses 38. In this case the knife may thus be ground again until it has been worn down so much as to cause the bolts to reach again the lower part of the elongated apertures in the chipper disc as shown in FIG. 2. The stationary washer 48 also has for its purpose to retain the bolts in the desired positions during adjustment operations by frictional engagement with the sleeves 54.

The spring 58 is suitably slightly prestressed. The portion 62 need not be located within the elongated aperture 42 of the knife 14 but may also be arranged to co-operate with any other elongated aperture through which the bolt 30 penetrates.

While one more'or less specific embodiment of the invention has been shown and described it is to be understood that this is for purpose of illustration only and that the invention is not to be limited thereby but its scope is to be determined by the appended. claims.

What I claim is:

l. A securing means for securing a blade or the like to the front face of a movable cutter element, said blade having an elongated aperture therein to aid in adjusting the position of said blade on said movable cutter element, and in which said movable cutter element is provided with a bolt hole extending to its rear face to receive said securing means, said securing means comprising a bolt body threaded at one end to extend through said movable cutter element beyond its rear face and having a flattened T-shaped head to be positioned at said front face, the width of said head being such that it can pass through said elongated aperture when parallel thereto and of sufficient length so as not to be capable of passing through said elongated aperture when at right angles thereto, and stop means on said bolt body adjacent said head to allow said bolt body to rotate in said elongated aperture a quarter revolution and to prevent rotation further than said quarter revolution, said stop means being positioned in relation to said head so that said head may be rotated, by rotation of said bolt body, from a position parallel to said elongated aperture to a position at ninety degrees to said aperture.

2. The securing means of claim 1, in which a helical spring is positioned about said bolt means with one end bearing on a shoulder formed on said bolt means near said head and with its other end bearing on a stop forming part of said movable cutter element so as to cause the nut when being turned to keep its axial position unchanged and so as to move the bolt means axially.

3. The securing means according to claim 2 in which said stop is in the form of a washer common to all the securing means of one knife and is formed with bolt holes of a shape corresponding to that of the bolt holes in said movable cutter element.

4. The securing means according to claim 3 including means to rigidly secure said washer onto said chipper disc.

5. The securing means according to claim 1 including projections on said bolt body adjacent said bolt head adapted, when introduced into the elongated apertures of the knife, to prevent said bolt body from any rotational movement.

6. The securing means according to claim 1, in which said blade is formed with two recesses merging into one another, the bottoms of said recesses merging with said elongated aperture, said recesses being shaped to receive the bolt head, whereby when in securing position said bolt head is sunk into said blade.

Smith Nov. 13 1934 Michael Mar. 29, 1949 

